Final answer:
The Church teaches that because it is composed of human believers, repentance and conversion are necessary due to humanity's proneness to sin, underscored by practices like baptism, communion, and confession as well as the outcomes of the Catholic Reformation and Council of Trent.
Step-by-step explanation:
The constant need for repentance and conversion within the Christian faithful acknowledges the human capacity for sin and the importance of sacraments as measures of spiritual renewal. During the era following the spread of Christianity in Europe, the Church's teachings revolved around the idea that a benevolent God and a force of darkness, Satan, coexist, with the latter aiming to lead humans into sin. The influential Catholic Reformation and the Council of Trent demonstrated the Church's response to internal corruption and external challenges, like those posed by Martin Luther's Protestant Reformation.
Faithful Christians, according to the Council of Trent, required both good works and faith for salvation, and the Church maintained its authority by declaring both scripture (as interpreted by the church) and tradition as valid. The significance of repentance was also underscored by identifying sins with various life challenges, such as illness or crop failure, suggesting divine disapproval.
Thus, the sacraments - baptism, communion, and confession - were critical in mediating the relationship between believers and God, emphasizing the Church's central role in moral guidance and the remission of sins.